It’s a good idea to have one downspout for every 20′ of gutter. Adding a downspout to your existing drainage system is simpler that you think but it does require several tools.
Here are the tools that you will need:
Screw in the two brackets, anchor may be necessary if going into brick.
Mark a 4″x3″ X that will be cut for water to drain out.
Cut the X using a razor blade.
Fold open the fins.
Here is a top view:
Hold up the two elbows and measure the gap between them.
Cut a filler piece for the gap between the downspout elbows.
Break out the crimpers.
Crimp the corners to allow the filler piece to be inserted into the elbow.
Install the filler piece between the elbows.
Hold the elbows on the wall where they go and mark where the downspout will slide up on the elbow.
Measure down to the top of a new elbow and up to your mark on the wall.
Pull your tape line from the factory crimped side of the downspout.
Mark the downspout length.
Cut your mark.
Assembly the complete downspout.
Shoot in a few zip screws in the joints to secure the downspout together.
Attach the downspout to the gutter.
Secure the downspout by using the straps.
Make sure you have a couple of inches of clearance under the downspout.
Enjoy the new downspout.